Coke oven construction



Feb. 8, 1944. o'r'ro 2,340,981

. COKE OVEN consmucwzou Filed May 3, 1941 2 Shets-Sheet 1 INVENTOR s? 63404 Orro 'H QZWa/M ATTORNEY Feb. 8, 1944.

c. OTTO 2,340,981

COKE OVEN CONSTRUCTION Filed May 3, 1941 2 Sheets-Sheet 2 INVENTOR Cfl/PL Orro ATTORNEY Patented Feb. 8, 1944 umrao STAT ES PATENT o 'FicE Carl Otto, Manhasset, N. Y.', assignor tov Fuel? Refining Corporation; Dover, Del., a corpora tion of Delaware Application May 3, .1941;:SeriaLNmBB'LGrH- a 11 Claims. lemme-222)? The generalobject ofthe presentinvention is to improve :theconstruction -and--operation of coke oven batteries or the horizontal coke oven type which comprise horizontally elongated coking" chambers? arranged side lay-side and extendin'g transversely oi the battery in alternation with "heating wallsformed-- with vertical heating fi'ues; andwhich are now'generally used throughout the worldin the manufacture of coke of the kind usedin blast furnaces'and for analogous metallurgical purposes.

A morespecifically"stated-general object of the invention "is "to'lmprove-the-construction of horizontal coke oven-batteries ln'respect to a characteristic"oftheir-heatingwalls which I designatetheirconductivitwstrengt characteristic. My improvement m're'spectto the'conductlvltystrength characteristic*of-acoke oven heating wall"permits that 'wallto be given increased strength to resist'lat'eral'stresses due to the-expansion of the coal being coked, or incidentalto the c'okedischarging operation without requiring any change in the. thickness of 'ltsfiue' walls or other change in thehorizontal cross-section of thewa'll. v A specific objecttof 'theinventionis to provide a horizontalcdk'e oven batteryinwhich the coking chamberheight is "greatenthan has heretoi'ore been'considered "safein'thl's country, and in which the heat conductivity 'of'the heating walls thereof'isa's great-as; or greater than has'been customary heretofore.

Another: specific object 'of "the present-invention is: toprovl'de'animprove'd method of coking expanding 'coals'," characterizedb the passage of the cokingfheat into the coking charge, or coal mass being" coked, through" fined heatin walls, which; because of the greater thinness of their flue walls, have a'highenheat conductivity and less inechanicalstrength than the heating walls of coke ovenshemtoiorehsed in coking such expanding coals'," and further characterized by the manner in whicl'ixforce 'is'impressed onthe heating"walls"toxenable them-to resist'the distortingstressesxxtorrwhlch they are subjected-by the expansionpfthe coal'being coked.

In accordancewith *thepresent invention I improve the conductivity-strength characteristic of coke"ovenheatingwallsand make it possible to supply coking heat' wan-expanding 'coal cokin charge throughheating-walls having higher heat conductivity than have-been used for thepurpose heretofore,-by subjecting'the upper edge of eachheatingwall to a-vertical "loading force substantially*irrexcesspf that' due to the'forc'e impressed :on..the heating: walls of.) horizontal coke, oven batteriesheretofore constructed by their. roofstructures. l 1; v

A propereunderstanding :Ofi JihB nature; of} the presenttinvention andrthe, manner in which it departsrfrom the-prior art maybe iacilitated by the followingexplanations; V

Theefiective heat conductivity of the heating wallsdeterminesiandistmeasured by the, quantity ratee'oi heat transferirom thefluesozf; aheating wall toz :cokingcharge in; anadjacent coking chamberwith; at. givenraverage.v heating wall flue temperature; .:A; coke -0V8Il, heating a wall oi the abovetmentionedmtype customarily includes so: cailedabinder 1 bricks which extend: transversely. of the heating wallscandaform-theflue divisionwalls, and runnerzbricks which extend longitudinally, of the heating.- walls and form the flue side walls directly. separatingthe flue spaces51romthe 00k:- ing chambers. The: effective heat conductivity at a :heating. wall is increased bycareduction in the thickness of: the, runner bricks cformingi the side. wallsof-t-he flue, and is alsov'increased my decreasing: the thickness. of the; binder. bricks, since sag-reduction inithep thickness' of the flue divisionwalls increases'the aggregate arealextent of the-.fiuepside .walls alongsideean; adj acent cokingychamber.

Thereffectivexheat; conducting capacity of a heating Mall :is, approximately 1 proportional,- to a. conductivity. factor .C, which is given in-Ja convenient iormtfor comparative purposes .by the following equationfA whereinr is theratio of the average width, meas- .ured parallel to the lengthier the heating wall, of its vertical flues, t0 the sum. of that width and the average thickness of thetransverse flue divisionwalh-and whereinit is the average thick ness, measured in. inches, of the flue "side walls directly separating the flue :spaces ofthe heat,- ing wall-from :the cokingtcharge. at one side-0f the:heating-wallnieln, most coke ovens'recently built andhowhunder construction in this countrygthe said conductivity factor .Ctis-abQut 13.

.Inthe constructionrof horizontal cokepoven batteries there has .been throughout the "last .quartericenturyza general tendency tostandardizationiin mespect to" various imatters of dimension andidormpalthoughxdurin that' period there has beeir a substantial increase in the "height and length'nf :coking' chambers In most such coke ovens constructed inth'e' last quarter-century the distance between the vertical central planes of adjacent coking chambers has not varied greatly from forty-three and One-half inches, and the average thickness of flue side walls has been about, or a little more than four and one-half inches, and the thickness of the flue division walls has usually been six inches or more, and the average width of. the coking chambers has not varied greatly from eighteen inc hesQthough during a portion of the Period some oven'batteries were built in which the coking chamber width was materially reduced in accordance with a subsequently discarded theory that such reduction was advantageous because of thereduction in coking time which it made possible.

tically desirable coking chamber height for use in coking non-expanding coals is about twelve feet, and that with such a coking chamber height the maximum safe and practically desirable conductivity factor C is about 13.

I have discovered, however, that by suitably increasing the roof weight or loading force on thetops of the heatingwalls I make it practically feasible and safe to-fcon'str'i c orizontal coke oven batteries in which the cokihgchamber height varies from twelve feet up to or somewhat above fifteen feet and in which the heating walls In most coke ovens of the above mentioned type constructed during the last quarter century, the thickness of the coke oven cover or roof over the coking chambers has been about three feet, except that in so-called cross-over ovens the coking chamber roofs customarily have been about three and three-quarters feet thick. The coke oven roof thickness standards appear to have been adopted and determined as the result of an early realization by'coke oven designers and builders that-:unlessthe masonry cover or roof over ordinary coke oven chambers is about three feet thick, the heat radiation losses at the top of the battery will be objectionably large and the workers moving about over the top of the battery will be subjected to undesirably high temperatures. Additional roof thickness is necessary in cross-over ovens to avoid excessive roof temperatures and heat radiation losses, because of the roof heating action of the cross-over flue connecting passages above and through which heating gases pass over coking chambers.

At the time at which the roof thicknessof coke oven batteries of the most usual form of the above mentioned type became standardized at approximately three feet, the coking chamber height in such batteries was ordinarily about ten feet or less and their heating walls had a conductivity factor of about 11 or 12. At thepresent time, however, the art demands that the oven chamber height be substantially greater than ten feet in order that the oven chamber volume or capacity may be correspondingly large. It is now generally recognized in the art, also, that the conductivity factorC- of coke oven heating walls should be as large as is practically possiblefor the reason that any increase in that factor results in a reduction in: the flue temperatures required for operation with a given coking time, and for the further reason, more important from a practical standpoint, that any increase in that factor permits of a corresponding reduction in the coking time obtainable with a given maximum flue temperature. e

Heretofore, however, coke oven designers and builders have not been able to increase the coking chamber height and the effective heat-conducting capacity of the heating Walls or coke oven' batteries as they desired, because the strength of a coke oven heating wall to withstand lateral pressure is approximately in inverse proportion to the square of the vertical extent, or height, of the wall, and because the only mode of increasing the lateral stress-resisting capacity of such a wall, heretofore known and practiced in the art, has been -to=increase the thickness of the flue walls,.whereby the effective heat conducting capacity of the heating walls is reduced. In, this country it is now generally assumed that the maximum safe and prachave a heat conductivity factor C of, or larger than 13, and in which the heating walls have as much strength to resist lateral stresses as is customarilypossessed by the heating walls of commercial horizontal coke oven batteries constructed in this country in recent years. Moreover, I may obtain this advantageous result without making any changes in the cross sectional form and dimensions of the heating walls,.unless and except as the thickness of the flue wallsvmay be reduced to increase the heating wall heat conductivity.

The general tendency of a lateral stress impressed against and distributed over'ione side of a coke oven heating wall and large enough to distort the wall, is to divide the wall into upper and lower sections andtotilt those sections as they would tilt if they were hinged together'at the side of the wall on which the thrust lsfimpressed, and if they were respectively hinged at the opposite side of the wall to the adjacent horizontal oven roof and floor' 'portions of the battery structure. Such tiltingmovements of the upper and lower walls'ections are opposed both by the roof load carried by the wall, and by the weight of each wall section, and cannot occur without lifting the adjacent roof structure and raising the center of gravity vof each wall section. A I 4 As will be apparent, the resistance to thewall section tilting movement of each pound'of wall weight will be only half that due. to each pound of roof weight. In consequence, the'reduction in the strength of a heating wallto resist lateral thrust which a reduction in the heat n W'all weight resulting from a reduction in 'the thickness of its flue walls tends to .piioduce,. may be compensated for by'adding to the roof load on the heating wall, half of the weight taken away from the heating wall. i

In the usual coke oven batteryfthe roof struc-' ture is subjected to a compression force or load acting between its edges and-due to th'elt'en'sion of the tie rods connecting] the buck stays at the opposite sides of the battery. Inconsequence, any distortion of a heating wall resulting from a lateral thrust impressed on it and tending to distort and raise the roof'structure, is opposed by the tie rod tension force acting von the roof in the same general manner in,which theroof load on a heating wall tendsto prevent its distortion under a lateral thrust. 3 As will. beap parent, with a given tie rod tension, the roof opposition to the heatingwall distortion will be approximately proportional to. th'eroof, thickness.

As a result of my computations,observations, and considerable experiencei'n 'desig'ning'and constructing horizontal coke oven batteries,I.am of the opinion and'beliefthat l650f pounds per foot of heating Wall length is about the safe-minimum heating wall loading force ina coke oven battery which is of usual form and; isiusedfin coking non-expanding coal, and in which the coking chamber height-is twelve feet and the heating wall conductivity factor- C is 13, and in which the cokeoven roofis three anditwo-third's feet thick and is subjected to the usual-cross tie rod tension.

In general, when the minimum safe heating wall loading force specified in the preceding par--- In theforegoing equation, L is the heating wall;

loading force in pounds perfoot of. heating wall length, 1-1 is the heightof thej coking chamber measured in feet, T is the thickness of the coking.

chamber roof measured in feet, Wis any reduction in heating wall weight per, foot. of. heating wall length which may, result from an increase in the heating wall conductivity factor above '13, and a, b, and c are coeflicients. having values which vary with conditions.

In general, the coefficient a will be equalto unity for a coke oven battery designed to coke non-expanding coal, and for a battery designed: to coke an expanding coal (1 will exceed .unity by an amount proportional to the assumed unbalanced maximum thrust of the expanding coal charge against the heating wall. In the case of a battery designed to coke non-expanding coal, the. coefficient 2) will ordinarily be not less than .9 nor more than 1, and in the case of an oven for cok-. ing an expanding coal the coefficient 1) should. ordinarily be increased in proportion to the de-. scribed increase in the coeflicient a.. In a coke oven battery formed of masonry of the. usual type and having a density of about one hundred and twenty pounds per cubic foot and, subjected to. the usual cross tie tension and in which the roof. thickness is increased above three and'two-thirds feet as required to provide the roof weight needed to give the proper loading force, L, the proper value of the coeflicient will ordinarily benot less than .9 nor more than 1.,

When in accordance with the practice of the prior art, the strength of aheating wall is increased by increasing he thickness of its flue walls along the length of the lattenthe strengthening effect of the added wall weight diminishes from the bottom to the top of the wall. When the added weight is all included in the roof load carried by the heating wall, its strengthening effect is uniform from the bottom to the top of the wall. This difference is of especial significance in the use of the presentinvention in cokingexpanding coals,.since the expansion of the coal charge tends to subject the heating walls to substantially the samelateral pressure at all levels. My improved method of coking expanding coal thus makes possible the broadly novel resultof increasin the strength of the heating walls to resist the lateral thrust, against the adjacent heating walls of the expanding charge in proportion to saidthrust at alllevels.

While the increase in the loading force on the heating walls made in accordance with the present invention may advantageously be provided in many cases by simply increasing the thickness of the oven cover" or roof structure so as to correspondingly increaseits weight, the loading force increase need not-be obtainedin-that manner'. On the contrary, in addition to, or in lieu of in creasing the heating wall loading force by'increasing the roof thickness, thatforce-may'be increased by the use of various mechanical expedients, one of which is hereinafter described.

Moreover, in coking a charge of an expanding coal ofsuch character that each charge exerts-a substantial lateral thrust against the adjacent heating walls during a certain portion-only ofits coking period-the loading force needed to compensate for the thrusts which the expanding,

I charges impressed on the different heating walls may be provided only during the periods in which such force is needed. To this end I may make use of a suitably weighted car or carsrunning' on track rails mounted on and extendinglongitm. dinally of the battery.

The various features of novelty which characterize my invention are pointed out with partied-- larity in the claims annexed to and forming a part of this specification. For a better'und'em standing of the invention, however, its: advan-: tages, and specific objects attained with its use,

reference should be had to the accompanyingvv drawings and descriptive matter in which I have. illustrated and described preferred embodiments of the invention.

Of the drawings:

Fig. 1 is a partial transverse vertical sectionof: a horizontal coke oven battery with parts brokenaway, and with its left-hand portion taken onthe line i-l and its right-hand portion taken on the line lA-EA of Fig. 2;

Fig. 2 is a partial vertical sectiontaken on the line 2-2 of Fig. l;

Fig. 3 is a partial horizontal section taken on the line 3-3 of Fig. 1;

Fig. 4 is a partial vertical section takensimilarly to Fig. 2 and diagrammatically illustrating the manner in which a heating wall may be distorted by a lateral thrust;

Fig. 5 is a partial elevation taken similarly to Fig. l, but on a larger scale;

Fig. 6 is a partial section on the line 6-45 of Fig. 5; and

Fig. '7 is a somewhat diagrammatical transverse vertical section of a coke oven battery including amodified form of heating wall brick arrangement.

In the drawings and referring first to the con-#- struction shown in Figs. 1-6, A represents the, deck or slab directly supporting the coke oven brickwork of a horizontal underfired coke oven battery which may be of any one of various knownforms, and, as shown, is or the general type and form disclosed in my prior Patent No. 2,216,983. The deck member A is customarily in the formof a reinforced slab or slabs of concrete and is supported by beams A and columns A the latter extending upward from a foundation, not shown, through the basement space B which is a characteristic feature of anunderfired coke oven battery and has its roof formed by the deck A.

The coke oven brickwork mass supported on the deck A comprises upper and lower storiesi The upper story includes horizontally elongated coking chambers C alternating with heating walls D. Each of the latter is formed with vertical flues d alternating with short vertical fiues d. Each flue d and an adjacent flue d are connected at their upper ends to form a twin or hairpin flue. The lower story is formed with alternately disposed regenerator chambers E and e extending transversely. ot the: battery and shown as alter mating with one another. As shown, each of the regenerators E and e is separated from the adjacent regenerator e or E at its left-hand side as seen in Fig. 2 by a pillar wall F directly beneath a corresponding heating wall D, and is separated 5 from an adjacent regenerator e at its right-hand side as seen in Fig. 2 by a regenerator division wall ,1. The branch d of each twin flue is connected by passages E and e to the two adjacent regenerators E and .e at one side of the subjacent pillar wall F, and the associated flue branch d is connected by passages E and e to the two regenerators adjacent, but at the other side of said pillar wall.

. As shown, rich gas ,fuel may be supplied to high and low burner outlets D and D respectively, in the different flue branches (2 and d through channels g extending upward through the regenerator division walls ,2. The regenerators E and e may be identical in construction, but in the battery shown, the regenerators E are intended solely for use in preheating combustion air; and the regenerators 6 may be used in preheating either lean gas or combustion air accordingly as the battery is being heated by the combustion of lean gas or rich gas.

The body portion of each heating wall is formed by runner bricks H and binder bricks I arranged in superposed courses. Each course includes runner bricks H extending longitudinally of the heating wall forming the side walls of the flues d and d separating the latter from the adjacent coking chambers, and the binder bricks I of each course extend transversely of the heating wall and form the transverse flue division walls. As shown, the bricks H and I are of conventional form, each being formed with a rib at its under side and a groove at its upper side to provide tongue and groove interlocking between the bricks inadjacent courses.

. The portion of each heating wall above the flues d and d is formed of superposed courses of bricks ha, some of which are perforated or notched to provide the usual inspection holes (I in line with the flues d and d. The heating wall brickwork course including the upper end portions of the flues cl and d, comprises specially shaped runner bricks HA and binder bricks IA and IB. Each binder brick IB, as shown, comprises a lower portion I which, in eilect, serves as the corresponding binder brick of the subjacent brick course, and above said portion I is notched or cut away to provide a passage I through which the adjacent flues d and (2 communicate. As shown, and as is customary, the binder bricks IC at the outer side of each flue d or d" at the end of a heating wall are formed with curved outer sides for engagement by the socalled saddle bricks which form the outer end portions of the heating walls, and each of which is directly engaged by the corresponding vertical buck stay J.

-The masonry battery roof or cover above the level of the upper edges of the coking chambers comprises superposed courses of bricks or refractory blocks K, and may be, and as shown, is of conventional form except that it is formed with grooves K extending down into the roof from the top surface of the latter and each open at its upper edge and extending transversely across the battery directly above a corresponding heating wall.

Except for its roof grooves K the coke oven battery structure shown in Figs. 1-3 includes nothing hereinbefore described, which is claimed as'novel herein, and is illustrated as an example of one of the various types and forms of horizontal coke oven batteries in, and in connection with which, use may advantageously be made of the present invention. Each of the roof grooves K receives a corresponding beam L which forms a means through which the loading force impressed on the top of the subjacent heating wall by the weight of the roof structure, may be supplemented by force impressed on said beam L. As shown, each beam L is formed of reinforced concrete, the reinforcement being shown as comprising two channel bars L' and a plurality of rods L I The means shown for applying a loading force to each beam L comprises a compression spring M at each end of the beam above the latter and acting between it and a spring abutment N rigidly secured to the corresponding buck stay J. As shown, each abutment N is formed by a short horizontal angle bar having one of its flanges vertically disposed and bearing against the inner edge of the corresponding buck stay J and having its ends'projecting beyond the opposite sides of 25 the buck stay J. Each abutment N is secured to the corresponding buck stay by means permitting its vertical adjustment and comprising rods N, nuts N and a yoke or cross head member N As shown, the member N is a horizontal channel bar 30 engaging the outer edge of the buck stay and the bars N have their outer ends threaded for engagement by the nuts N and have their inner ends welded to the ends of the corresponding abutment member N and extend through open- 35 ings formed in the base or bottom portion of the yoke N against the outer side of which the nuts N bear. As shown, each of the springs M is a. leaf spring having its ends resting on the corresponding bars L and is subjected to regulable 40 compression by means of an adjustable screw N which is threaded through a nut N welded against the under side of the horizontal flange of the abutment member M and which bears against the upper side of the spring M, midway between the bars L As shown, the channel bar reinforcing members L incorporated in each beam L form parts of a tie rod connection between the two buck stays J at the opposite ends of the corresponding heating wall. To this end, in the construction shown, each member L has welded to its outer end a bar 0 which projects past the corresponding buck stay and has its outer end threaded and engaged by a nut O. The latter serves as an abutment for the outer end of a compression spring 0 acting between the nut and the corresponding end portion of a cross head or yoke member 0 which may be identical with the previously described cross head N Each buck stay K is anchored at its lower end to the battery masonry. The anchoring means shown comprises a horizontal angle bar section P welded to the inner edge of the buck stay and embedded in the deck A, and anchor bolts 0A having their inner ends extending into and anchored in the deck A in the customary manner, and resiliently pressin the lower end of the buck stay against the side of the battery by means of corresponding nuts 0' and springs 0 similar to those acting on the upper end of the buck stay.

In Fig. 4 I have illustrated the manner in which a coke oven heating wall subjected to an insufficient loading force may distort under the action of an unbalanced lateral thrust applied in the direction shownby the arrows against oneside of the wall- Inconsequence of the tongue and groove connections or other bonding connections between ,thesuperposed bricks, the

resistancetohorizontalmovement of the top and bottom edges ofthe heating walls relative to the oven roof and floor masonry andto horizontal relative movement of theheating wall bricks in adjacentcourses is such that the "usual effect of a lateral distortingthrust is=to bend or bowthe wall; in ,a manner, somewhat analogous to'that in whicha beam. supported at-its ends bows under a load heavy enough to produce a partial .failure or -fgreen .bough fracture of the-beam. As is illustrated in exaggerated form in Fig. 4, upper andlower-portions of the ,wall tilt or-bend relative to one another about.;a horizontal axis at the sideofthe wall against which the thrustis applied -.a nd nearer to the top than to the bottom-of the ,wall. Inconsequence, the joints between the superposed brick courses at the level ofsaid axis open at the convex. side of the wall, as indicated at D and at the-top and bottom .of the heating wall, brickwork joints open at theconcayeside .ofthewall, asindicated at, D

It shouldbenoted that-the mortar interposed between the bricks ahacoke oven heating wall does not, andis not expected to have anybonding or adhesive actionsignificantlyopposing the tendency of the brickwork joints to open as indicated in Fig. 4. Any-separation of the adjacent brickcourses ,tends clirectlyto gas leakage between the heating wall flue spaces'and the adjacent coking chamben, Moreover, .a coke oven heatingwall bentin one direction as shown in Fig. 4, as a result of the expansion of one coal charge at one side of the wall, will normally be subjectedv to similar distorting stresses applied alternately to its opposite sides. vThe successive .bendingl movements of the wall alternately in oppositedirections, tend in time to effect disintegration of the mortar between the bricks in adjacent courses, andthereby indirectly roduce obj ectionable. leakage, .even though each individual bending-movement is relatively minute and has little tendencytoproduce significant open joint leakage.

As will be apparent,- the heating wall would not bend and have its brick work joints open as shOWn'in Fig. 4, ifa-sufficiently large loading force were impressed on the-top of the wall.

The unbalanced lateral thrust of anexpanding coking charge against a heating wall. alongside the charge is approximately uniform from the top to the bottom of vthechargeand the gravitational-thruster the. charge against the wall increases from the top to. the bottom of that wall. Normally, however, the. maximum displacement of the wall. away.;from the;verticalplane of the top and bottom edges of the .side of the wall distorted-by-an expanding charge, occurs at a. level appreciably nearer tothe. top than to the bottom of the wall. Thisresults from the fact that the :weight .of the heating ,wall .bricks' subjects the wall fto a loadingforce which tends to prevent the wall bending illustrated in Fig.4 and which progressively diminishes from the bottom to the top of thewall.

To facilitate aproper appreciation of the present invention, itmay be'helpful to consider the changes in the minimum safe heating wall loadin force provided inaccordance with .thepresent invention'which wouldresultfrgm certain definitechanges in lthedimensions of the coke-oven structure shown-in Figs. ,1, 2 and 3 of the accom panying drawings.

Thus, for example, let us first assume that in said structure the-distance between the coking chamber centers is forty-three and one-half inches, the average width of each coking chamher, which may have the usual taper, is eighteen inches, the coking chamber height is twelve feet, the average thickness of the walls formed by the runner bricks H between the vertical heating fiues and the adjacent coking chambers is four and five-sixths inches, the thickness of the flue division walls formed by the binder bricks 1 is six andone-half inches, the horizontal flue dimension in the direction of the heating wall length is eleven inches, and the coking chamber roof is three and two-thirds feet thick.

With the foregoing assumptions the heating wall conductivity factor C, determined in accordance with the previously stated equation A, will be approximately l3, and as previously stated,

the minimum, safe heating wall loading force required in coking a non-expanding coal will be approximately 1650 pounds per foot of heating wall length. That loadis a little more than ten per cent greater than the maximum load impressed on the heating walls of any prior horizontal cokeoven battery known to me and having such dimensions-as are assumed above. I

Let us nowconsiderwhat changes in the heating wall loading force should be made when, for example, thecoke oven dimensions assumed above are changed as follows; namely, when the cokingchamber height is increased -from twelve feet to fifteen feetand the average thickness of the fiue. side walls formed by the binder bricks H is decreased from four and five-sixths inches to four inches and thethickness of the flue division walls formed bythe binder'bricks I is decreased from six and one-half inches to six inches. The described changes in the thickness of the flue walls will increase the thermal conductivity factor (3, asdetermined by equation A, from approximately l3 to approximately 16.43, and results in a. reduction in the weight ofthe heating walls at the sides of the fifteen foot high coking. chambers of about one hundred and thirty-fivepounds perfoot of heating wall length. Such reduction. in heating wall weight'should be compensated for, in accordance with Equation 3, by an increaseinthe heating Wall loading force of approximately sixty-seven and one-half pounds. H

In accordancewith Equation B, the assumed increase in ,cokingchamber height from twelve feet to fifteen feet, considered by itself, should result in anincrease inthe minimum safe heatingwall loading force per foot of heating wall length from 1650 pounds to 2578 pounds. The total minimum loading force per foot of heating wall length required by Equation B when the oven chamber height is fifteen feet and the fiue and flue wall dimensions arethose last mentioned, is thus2645 /2 pounds. Of that loading force approximatelyl480 pounds may be assumed to be provided by the weight of the roof when the latter is three and two-thirds feet thick and of the usual construction and density. In consequence, compliance with Equation B will be effected if a loading force is applied to each beam L through the corresponding springs M of approximately 1145 pounds per foot of heating wall length. This beam loading force for an oven in which the heating wall length is forty-three feet, requires the transmission of a loading force to between its ends generally each end of each beam L through the corresponding spring M of a .little less than 25,000 pounds, which is quite feasible.

' As already indicated, ordinarily I consider it practically preferable to provide the heating wall loading force required in the use of my invention, 'by'increasing the weight of the coke oven roof structure, particularly since when the roof thickness is increased less loading force is required than when the roof thickness is not increased. Thus, for example, if the above mentioned conditions requiring a roof load per foot of heating walllength of about 2645 pounds, are modified .merely by an increase in roof thickness from three and two-thirds feet to five feet, the heating wall loading force per 'foot of heating wall length needed to satisfy Equation B is assumed to be equal to unity, as it may well be under the conditions described. With the coke oven roof formed of masonry of the customary character and density, the weight of the five foot roof will provide a heating wall loading force per foot of heating wall length of approximately 2,000 pounds.

To secure the maximum wall strengthening eifect practically obtainable by increasing the roof thickness, the roof must be subjected to an adequate cross tie rod compression force opposing any tendency of the roof to distort and lift as a result of the distortion of the subjacent heating walls, and to this end the roof must be formed to restrict its freedom to bow upwardly as Fig. 4 shows a heating wall bowing laterally. To this end I may advantageously curve the brickwork courses extending between the sides of the battery in the upper portion of the latter so that the center of each of said courses is lower than the ends of the courses. In that figure the beams L are omitted and the opposing buck stays J, which may have their lower ends connected to the battery structure as in Fig. '7, are shown as having their upper ends connected by a tie rod LA and springs LA of customary form.

In Fig. 7 the deflection the courses progressively diminishes from the top of the battery downward. The deflection from the horizontal of the brickwork courses including the runner and binder bricks H and I may well be produced by making the thickness of the mortar in the joints between superposed courses greater adjacent the sides of the battery than adjacent the center of the battery. Advantageously, however, in the battery roof structure, in addition to such variations in the joint mortar thickness, use may well be made of bricks or .shapes adjacent the sides of the battery which have greater vertical thickness than the corresponding bricks or shapes in the same course adjacent the center of the battery.

' In Fig. 7 I have also illustrated provisions for moving weighted bodies P longitudinally over the top of the battery in the direction of the length of the latter to thereby increase the loading force applied to the top of each heating wall during the portion of its coking period in which a charge of expanding coal coking in an adjacent oven exerts its maximum lateral thrust against said heating wall. As shown, the weights P are in the form of cars running on track rails Q adjacent the sides of the battery. By loading the cars with pig iron, pig lead, or other available material having a relatively high spciflc gravity, the weight required may be provided without requiring the carsto extend into the path of movefrom the horizontal of j ment of the usual lorry car or cars It running on track rails S and employed to charge the oven chambers through their roof charging holes T. As will be apparent, the track rails Qand weighted cars P may be added to existing batteries used to coke expanding coal and having an adequate heatingwall strength.

If desirable to mini'mize the coke oven roof thickness, the roof may be formed of vor include materials having'a substantially higher density than ordinary masonry, by including in its struc* ture magnesite or 'chromagnesite bricks which have a substantially higher density than ordinary silica or clay bricks. The weight of the roof structure may alsofbe increased without correspondingly increasing its height by including pig iron in its upper portion. .As previously indicated, however, the heating wall loading force required in an oven having given coking chamber and heating wall dimensions is lower when the oven roof is relatively thick than when it is relatively thin, even though the roof weight is the same in each case.

From the foregoing explanations it will be apparent'that in designing and constructing coke ovens use should be made of the principle that the loading force on the heating walls of modern high chamber ovens should be greater than has been customary and should increase as the oven chamber height is increased above twelve feet with proper allowances for variations in the roof thickness and the heating fiue and fiue wall dimensions in the general manner indicated by the foregoing Equation B.

In practice, the use of said principle and equation requires the assignment of values to the equation constants or coefiicients a, b and c, which are based upon assumptions and estimates primarily as to. the character'and magnitude of the distorting lateral forces acting on the heating walls, and secondarily as tothe character of the batterymasonry and the eflectthereon of the strains to which it will be subjected in its extended use. The accuracy of those assumptions and estimates must ordinarly depend, obviously, on the skill'an'd experience of the designer and his knowledge concerning the working conditions to which the battery will be subjected.

In this connection we note, for example, that while it is possible to accurately compute the precise heating wall loading force required to neutralize the wall distorting effect of the gravitational thrust against a heating wall which would be exerted by the charge in an adjacent coking chamber if the charge acted against the wall as though it were a liquid having the density of the actual coal charge, the actual gravitational thrust of the charge against a heating wall cannot be definitely predetermined, as it depends upon such variables as the physical characteristics of the coal coked, and the rate at which gas is evolved from the charge during the oven charging operation.

It is readily possible to accurately compute the precise amount of heating wall loading force necessary to compensate for a given uniform distributed lateral thrust against a heating wall by an adjacent charge of expanding coal. For example, if that thrust amounts to a quarter of a pound per square inch of heating wall surface engaged by an expanding charge extending to within a foot or fourteen inches of the roof of a coking chamber fifteen feet high, the amount of heating wall loading force per foot of heating wall length needed to balance thatthrust when the .heating wall: is of customary thickness .will be about nine hundre'dupounds. In :practice, however, it will: ordinarily not be possible i to maccurately predetermine the- :precise maximum value of the unbalancedthrust against a heating wall due to the expansion of an-adiacent coking charge. That value will depend-not only on characteristics of the coal'coked and other'conditions which determine the magnitude of the-thrust exerted by a coking charge atone sideof the wall, but will also depend upon the relation ,between the thrust impressedon the heating wall by the coal-charge at the-opposite sides ofqthe wall. The maximumaresultant o'f :thethrusts of the two charges will dependinipart upon the relative times at which the two charges are put into the respective ovens.

Said Equation B, like the .equations and formulae customarily used in designing bridges and otherstructures, should include a substantial safety factor. In consequence, an appreciable reduction in the minimumheating wall loading force determined in accordance with Equation B can ordinarily be made :without :necessarily or probably resulting in-a breakage: of the. coke oven heating walls. However, the-fact that coke ovens of the type under consideration, which have a heating wall loading force appreciably smaller than the minimum required by compliance :with Equation .13 may have sufiicientstrength to insure a reasonable long operative lifeunder favorable. operating conditions, does not alter the fact that for satisfactory: and-safe operation horizontal coke oven batteries having a chamber height oftwelve feet or more should have'their heating walls subjected to aloadingiforce'which is substantially greaterthan has been heretofore customary,; and which may advantageouslybedetermined by use of the saidEquation B.

It is a minor advantage of the invention, also, that when the ,weightof va heating'wall .is reduced and the effect. of the'weightreduction on the-heating wall strength is compensated for by anincrease in theroof weight,;a significant decrease in the constructionzcostiof the coke. oven battery is effected. Thisresults from -the'fact that the. silica shapes used in the construction of the coke oven heating walls cost about three times as much per ton as the smaller weight of bricks added to the coke oven roof to compensate for the silica shapes weight eliminated from the heating walls.

While in accordance with the provisions of the statutes, I have illustrated and described the best forms of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention, as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A horizontal coke oven battery comprising horizontally elongated coking chambers with a coking chamber height not less than twelve feet and heating walls alongside said chambers and formed with vertical heating fines, and means for subjecting the top of each heating wall to a loading force which is approximately proportional to the square of the oven chamber height and is approximately 1650 pounds per foot of heating wall lengthin a battery in which the oven chamber heightlis twelve feet, and in which the heating wall width, the horizontal dimensions of the fiuesandthe battery roof thickness are of customary order.

2. A coke ovenbattery as specified in claim 1 in which the oven chamber height exceeds twelve feet and the roof-thickness is in excess of three and two-thirds feet an in which said loading force is reduced'in'proportion to said excess.

3. A coke oven battery as specified in claim 1 in which the customary horizontal fiue dimensions are modified to increase the effective heat conductivity of the wall with a resultant reduction in the weight of the heating wall and in which the loading force on the heatingwall is increased by an amount equal to half of the said reduction in heating wall weight.

4. A horizontal coke oven battery structure comprising horizontally elongated coking chambers and heating walls alongside said chambers, vertical buck stays at theends of the heating walls, connections between said structure and buck stays preventing up movement of the latter relative to the structure, a beam above each heating wall, and, means connecting the ends of each beam to thebuck stays at the ends of the subjacent heating wall and subjecting the beam to downwardly acting'force augmenting the loading force on said heating wall due to the weight of the battery roof.

5. A horizontal coke oven battery structure as specified in claim 4 in which the beam and buck stay connections comprise resilient means and said force is a resilient force to which the beam is subjected by said resilient means.

6'. A horizontal coke oven battery as specified in claim 4E in which the upper portion of the battery roof is recessed toreceive said beams.

'7. .A horizontal coke oven battery as specified in'claim 4 in which each of said beams is made of reinforced concrete.

8. A horizontal coke'oven battery, as specified in claim 4, including means connecting each of said beams to the corresponding pair of buck stays and subjecting the beam to regulable tension whereby the'latter serves as a tie rod connection between the last mentioned buck stays.

9. A horizontal coke oven battery structure comprising horizontally elongated coking chambers with a coking chamber height in excess of twelve feet and heating walls alongside said chambers and formed with vertical heating flues, and a roof the weight of which subjects the top of each heating wall to a loading force per foot of heating wall length which is approximately equal to the diiference between an amount in such proportion to the square of the oven chamber height that it would be approximately 1650 pounds if the oven chamber height were twelve feet and an amount proportional to the excess of the roof thickness over three and two-thirds feet, and in which the heating wall width, the horizontal fiue dimensions, and the battery roof density are of customary order.

10. A coke oven battery as specified in claim 9 in which the customary horizontal flue dimensions are modified to increase the effective heat conductivity of the wall with a resultant reduction in the weight of the heating wall and in which the loading force on the heating wall is increased by an amount equal to half of the said reduction in heating wall weight.

11. A horizontal coke oven battery comprising horizontally elongated coking chambers about fifteen feet high and comprising heating walls alongside said chambers and each formed with vertical flue spaces and transverse division walls of such thickness that the aggregate width of said flue spaces is not less than about sixty per cent of the heating wall length and the average thickness of the portions of each heating wall between its flue spaces and a coking chamber alongside said wall being about four inches, and comprising means for impressing a loading force on the top of each heating wall not less than about twenty-five hundred pounds per foot of length of each heating Wall less an amount which is proportioned to excess if any in the roof thickness over three and two-thirds feet.

12". In coking an expanding coal in the coking chambers alternating with the vertically fiued heating Walls of a horizontal coke oven. battery, the method which consists in increasing the strength of the heating walls to resist the unbalanced thrust thereon of the expanding coking charges by impressing a loading force on the tops of said walls proportional to said unbalanced thrust.

13. In coking an expanding coal in a coking chamber receiving heat from heating walls at the sides of the chamber and formed with vertical heating fiues, the method which consists in increasing the heating wall strength as needed to resist the lateral thrust of the expanding coal by applying a vertical loading force to the top of each heating wall.

14. In constructing a horizontal coke oven battery, the method which consists in subjecting each heating wall of the battery to a loading force of the order of 1650 pounds per foot of heating wall length when the oven chamber height is about twelve feet and the thickness of the battery roof does not exceed three and twothirds feet, and compensating for an increase in the oven chamber height by increasing said loading force in proportion to an increase in the square of the chamber height, and reducing the increase in said loading force in proportion to the increase in the roof thickness when the increase in oven chamber height is attended by an increase in roof thickness above three and twothirds feet.

15. In constructing a. horizontal coke oven battery in which the coking chamber height is not less than twelve feet and in which the heating walls and roof are of customary thickness, the method which consists in subjecting each heating wall of the battery to a loading force in such approximate proportion to the square of the oven chamber height as to amount to about 1650 pounds per foot of heating wall length when the oven chamber height is twelve feet.

16. In constructing a horizontal coke oven battery for use in coking an expanding coal, the method which consists in subjecting each heating wall of the battery to a loading force of the order of 1650 pounds per foot of heating wall length when the oven chamber height is about twelve feet and the thickness of the battery roof is about three and two-thirds feet, and compensating for an increase in the oven chamber height by increasing said loading force in proportion to the increase in the square of the chamber height and reducing the increase in said loading force in proportion to the increase in the roof thickness when the increase in oven chamber height is attended by an increase in roof thickness above three and two-thirds feet, and increasing said loading force in proportion to the unbalanced thrust on a heating wall of adjacent expanding charges.

17. A horizontal coke oven battery having its upper portion formed of brick courses running between the sides of the batteries and bowed so that the'portion of each such course adjacent the center of the battery is lower than the portions of the course adjacent the sides of the battery, buck stays at the sides of the battery, and a tension means connecting the upper end of each buck stay at one side of the battery to the upper end of a buck stay at the opposite side of the battery and directly opposing any tendency of the bowed brick courses to straighten when the distortion of the portion of said battery beneath said upper portion tends to raise the latter, and means acting between the battery and each buck stay holding the latter against up movement relative to the battery.

CARL OTIO. 

